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3 Sheets-Sheet 11 INVENTOR. Stephen B Yacura July Z, 1968 s. a. YAcuRAPUSHER FOIR KILN AND METHOD OF CHARGING KILNS Filed June 17. 196.6

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Stephen B. Yocuro u zq//W bm N mm vw United States Patent O 3,390,870PUSHER FOR KILNS AND METHOD OF CHARGING KILNS v Stephen B. Yacura,Indiana Township, Allegheny County, Pa., assignor to PullmanIncorporated, a corporation of Delaware Filed June 17, 1966, Ser. No.558,325 12 Claims. (Cl. 263-28) ABSTRACT OF THE DISCLOSURE Thisapplication discloses a continuous tunnel kiln (for ceramic ware etc.)in which a train is slowly pushed through the kiln, and a car isalternately pushed rapidly into the kiln. Separate, connected pusherlugs driven by a reciprocating piston give alternate fast and slowpushes.

This invention relates to apparatus for pushing ware carrying cars intokilns. It is particularly adapted for use in connection with tunnelkilns in which ceramic ware is pushed through the kiln from the entryend to the delivery end of the kiln.

It is common practice to fire ceramic ware by advancing it through acontinuous tunnel kiln having a variety of different temperatures atvarious points `within the kiln for the purpose of drying and/ orpreheating the ware followed by firing and cooling of theware. A commontype of arrangements embodies a tunnel kiln with tracks along which aplurality of cars carrying the ware may be advanced in end-to-endrelationship. The unfired green ware is loaded upon the cars which aredelivered to the entry end of the kiln, the cars are advanced, andcarloads of fired ware exit from the delivery end of the kiln. It isundesirable by reason of the temperatures within such kilns to haveapparatus within the kilns to move the cars. Moreover, it is cheaper andsimpler to avoid such power transmission equipment. It is desirable,therefore, to advance the cars through the kiln by pushing from therearward end.

The provision of a drying and preheating section at the entrance end ofthe kiln in advance of a heating section is desirable, but may also beomitted. The section in advance of the heating (or firing) section ofthe kiln is referred to herein as the preheating section whether thesection be used for drying or is simply that section outside a kiln inwhich cars are placed prior to charging them into the kiln. Thepreheating section may be employed solely for the purpose of evaporatingexcess moisture from the green ware, as by thecirculation of largevolumes of mildy heated gases aboutthe ware. -In such cases, thegases'are circulated under pressure to obtain optimum heat transfer andto, equalize conditions in all portions of the setting from the top tothe bottom. In some instances a mild heating may also be provided inthepreheating section as may be required'by operating conditions. l

In the subsequent heating (or firing) section where the ware is raisedto firing conditions, a high temperature is required and isprogressively approached by ware being pushed from the kiln entrance.The term heating section is used herein to denote that section of a kilnwhere ware advancing through the kiln is heated to firing temperature asdistinguished from drying and preheating. Gases in the heating sectionare commonly withdrawn from ports near the entrance end of the kiln andnear the floor so as to advance heated gases counterflow to movement ofware through the kiln and to avoid stratification within the kiln.

A door is commonly provided between the preheating section of the kilnand the heating section of the kiln to p ICC prevent the preheatingatmosphere from being drawn into the entrance end of the heating sectionby the negative pressure therein. Where a preheating section is notprovided, a like door is provided at the kiln entrance to preventatmospheric air from infiltrating into the kiln. The door must, ofcourse, be opened when a car is to be advanced into the heating section.It has, however, been difficult to secure satisfactory door operationwith the provision of elaborate interlock equipment and to charge a kilnquickly and to push it slowly without undesirable complications .ofequipment.

It is desirable that the door be open for only as brief a period as isnecessary to move each kiln car from the preheating section to theheating section. In order to obtain uniform firing of all ware it isdesirable that the cars in the kiln should be pushed on a substantiallycontinuous basis. Accordingly, it is desired that each car be introducedfrom the preheating section to the heating section as quickly aspossible, but the cars in the heating section be pushed on a virtuallycontinuous basis.

I provide pusher apparatus including power means and lug means in drivenrelationship to the power means and placed to advance ware in a kilnwhen the power means are operated. I further provide additional lugmeans in driven relationship to the power means and positioned toadvance ware within the kiln when the power means are operated. Iarrange said lug means and said additional lug means to be alternatelyoperable to advance ware within the kiln when the power means areoperated. I preferably provide first lug means positioned to advanceware within a heating section of the kiln, second lug means to advanceware from a heating section to the heating section of the kiln and thirdlug means to advance ware in the preheating section. I prefer to disposeall of said lug means in driven relationship to the power means andarrange said lug means so that the first lug means are operatedalternately and oppositely to the second and third lug means when thepower means are operated.

I preferably provide piston means having first lug means directlyoperable with said piston means and endless chain means connected tosaid second and third lug means and driven by the power means to movethe second and third lug means in a direction opposite to the first lugmeans. I prefer to drive the first lug means forwardly upon a slowstroke of the piston and to retract the first lug means and piston upona rapid stroke, thereby advancing the second lug means and third lugmeans rapidly.. In the preferred embodiment, the second lug means beginto advance ware from the preheating section to the heating sectionbefore the third lug means begins advance .of ware in the preheatingsection. In this manner lost motion is provided as well as space betweenthe cars to permit closing the door after charging. I prefer that thelug means comprise latches or dogs which engage the kilns cars upon aforward movement and which retract beneath the cars upon returnmovement.

Other details, objects and advantages of the invention will become moreapparent as the following description of the present preferredembodiment thereof proceeds.

In the accompanying drawings I have illustrated various presentpreferred embodiments of the invention in which FIGURE 1 is adiagrammatic plan view of a tunnel kiln embodying my invention;

FIGURE 2 is a cross-sectional view taken through the heating zone of thekiln; y

FIGURE 3 is a diagrammatical side elevation of the entry end of the kilnalso showing the pusher apparatus and some kiln cars with unnecessarystructural details omitted;

lFIGURE 4 is a plan view of the pusher apparatus shown in FIGURE 3;

FIGURE isa view of the structure shown in FIG- URE 3 with the pusherapparatus shown at a different point in its operating cycle;

FIGURE 6 is a side view of another form of pusher apparatus with thepower piston in retracted position;

FIGURE 7 is a side View of the apparatus shown in FIGURE 6 with thepower piston in extended position;

FIGURE 8 is a plan view of still another form of pusher apparatus withthe power piston in retracted position;

FIGURE 9 is a side View of the apparatus shown in FIGURE 8; and

FIGURE is a side view of the apparatus shown in FIGURE 9 with the powerpiston in extended position.

Referring to FIGURES 1-5, a kiln has an entrance end designated at 1 anda delivery end designated at 2. Ware is advanced through the kiln fromentrance end 1 to delivery end 2 on a substantially continuous basis.The kiln has rails 3 in the bottom section upon which kiln cars 4 areadapted to advance through the kiln upon wheels 4a. The cars carrypedestals S upon which the ware may be placed on Setters or in any othermanner convenient and satisfactory to the kiln operator. Thelongitudinal area occupied by the ware is designated by reference number6. The heating section is provided with burners 7 which are disposed oneach side of the kiln to heat and fire the ware. The burners arepreferably in off-set, staggered relationship (FIGURE 2) to promotevigorous circulation of the internal atmosphere, thereby expediting heattransfer to the ware. The kiln may conveniently be considered as dividedinto a number of units. A preheating zone 8 comprises three units 8a,8b, and 8c in which the green ware is dried prior to firing.

A heating zone 9 comprises an additional number of units 9a, 9b, 9c,etc. to 9k. A cooling zone 10 comprises units 10a, 10b, 10c, etc. to10g. Inspection doors 11 are provided in zones 8c and 9a and burners 7are provided in heating Zones 9b to 9k. Fans, generally designated 12,are provided at various points along the length of the kiln to introduceair into and exhaust air from the kiln structure at appropriate points.Crown fans 13 may also be provided in the kiln roof. Hot gases aregenerally exhausted at the entrance end of the heating section, and theflow of such gases is counterflow to movement of ware through the kiln.The invention does not reside in the kiln structure which is describedin general terms only as an aid to understanding the invention.

In preheating zone 8 substantial volumes of air are circulated by fansto evaporate moisture from the green ware and, perhaps, to aid insupplying mild heat to the ware. Heating zone 9 is maintained as aseparate zone with increasing amounts of heat being applied as the waremoves therethrough. Preheatng zone 8 and heating zone 9 are separated bya vertically movable door 14 (FIG- URES 3 and 5) which can be raised topermit kiln cars to be advanced from preheating zone 8 to heating zone9. After a car has been passed through, the door is lowered to preventexcessive gas flow from the preheating zone into the heating zone byreason of the differential in pressures.

It will be appreciated that there is to be no immediate and radicalchange of temperature from one point to another in the kiln. To thecontrary, the ware is to be steadily and evenly brought up to ringtemperature as it advances through the kiln.

A hydraulic fluid cylinder 15 is provided adjacent the entrance end ofthe kiln and has a piston rod 16. Cylinder 15 is valved so that piston16 has a slow extending stroke and a rapid retracting stroke. Lug 17 isprovided upon the end of piston rod 16 `and engages angle irons 18iitted crosswise upon the under side of the kiln cars. Lug 17 is hingedso that when it is retracted it will go beneath angle irons 18 withoutengaging them. When it is advanced, however, it does engage the kilncars. A rack 19 is connected to piston rod 16 and moves with it. Rack 19engages a pinion 20 mounted upon a rotatable shaft 21. A sprocket 22,also mounted upon shaft 21, engages the lower reach of an endless chain23 which extends over idler sprockets 24a and 24b. A second lug 25 ispositioned upon the upper reach of chain 22 adjacent cylinder 15. Athird lug 26 is positioned upon chain 22 adjacent idler sprocket 23.`Lugs 25 and 26 yare similar to lug 171 That is, they will engage thekiln cars upon forward movement but will drop beneath and will notengage the cars upon a rearward movement.

When the kiln is being operated, the fans 12 and 13 and burners 7 areplaced into operation to give a desired heat balance and aircirculation. Such operating procedures are well-known, and are variablewith the ring requirements. Where the `kiln is in operation and is fullyloaded, door 14 will ordinarily be in lowered position. When it isdesired to advance ware through the kiln, hydraulic pressure is appliedto piston 15 causing lug 17 to move in a forwardly direction (to theright in FIGURES 3 and 5) engaging a'kiln car in position 27 and movingit forwardly to position 28. The stroke is a slow, deliberate one andthe entire train of cars in the kiln is slowly advanced, pushing aloaded car from the delivery end for unloading. The stroke may, forexample, take fifty-five minutes for completion. When the stroke iscompleted and the pusher apparatus is in the position, shown in FIGURE3, car position 27 will be vacant. Door 14 is thereupon raised andpiston 16 immediately makes a rapid return stroke, taking perhaps oneminute in a total cycle of sixty minutes. The door may be operated froma limit switch (omitted from the drawings for convenience) or other typeof switch associated with the reversing valve upon the power piston. Atimer is commonly provided to sequence each cycle, allowing forirregularities in the pushing and charging speeds.

When piston 16 makes its return stroke, lug 25 engages the kiln car inposition 29, advancing it past open door 14 into kiln car position 27.Door 14 is then closed by further switch action which may be ofconventional form. By reason of the rapid advance of a kiln car fromposition 29 to position 27, door 14 is open for only a minimum time andthe disruption of temperatures and gas ow in the heating zone i-s heldto a minimum.

During the initial portion of the return stroke of piston 16, lug 26travels around idler sprocket 24a. After the kiln car in position 29 hasadvanced an appreciable distance, lug 26 will engage the kiln car inposition 30 and advance it and those ahead of it to door 14 in a solidtrain. A small space is left between a kiln car in position 29 and akiln car at position 30 by reason of the idle travel of lug 26 aroundidler sprocket 24a. Door 14 is lowered into that empty space.

Advance of the train of cars to door 14 leaves kiln car position 30empty and ready to receive a new car of green ware which can Ibe pushedinto position whenever convenient.

After firing has proceeded to the extent necessary, the cycle isrepeated. In this manner ware is advanced through the preheating zoneand thence through the heating and cooling zones.

Referring now to FIGURES 6 and 7, a dolly 31 is mounted upon ythe end ofa piston rod 32 operable in a hydraulic piston 33. Dolly 31 moves fromside-to-side (as shown in FIGURES 6 and 7) upon wheels 34. An endlesschain having an upper reach 35a and a lower reach 35b passes oversprockets 36 and 37. The bottom reach of the chain 3519 is attached to abracket 38 upon dolly 31. A lug 39 is retractably positioned on top ofdolly 31. It will retract when dolly 31 is moved to the right. A seriesof lugs 40, 41, 42 and 43 are attached to the upper reach 35a of theendless chain and likewise lretract when moved to the right. When thelugs move in the opposite direction they will engage kiln cars andadvance them into the kiln. If desired, several chains may be providedin parallel arlrangement and operation.

The dolly and chain arrangement is located beneath a kiln preheatingsection 44 and kiln heating section 45 of the type previously described.A vertically movable door 46 is positioned 'between thepreheating andheating sections't'o prevent gas flow from the preheating section to theheating section;

' In :FIGURE 6a kiln car 47 is shown at the end of a train'beingpushedthrough the heating section of the kiln. Additional kiln cars 48, 49 and50 are shown in the preheating section and a car 51 is located justoutside the preheating section prior to entry into that section.`FIG-URE 7 shows .the same cars at the completion of a pushingcyele.

' When dolly 31 and the kiln cars are in the position shown in FIGURE 6,dolly 31 is then pushed by hydraulic pressure applied in piston 33. Whenpressure is first applied there is,l virtually no resistance to movementand dolly 31 is caused to advance promptly until lug 39 engageskiln car47. The advance is then adjusted to a much slower speed for pushing.Such speed changes are provided by conventionaly equipment which neednot be described here. The entire train is pushed slowly until thepiston has reached the end of its stroke, as shown in FIGURE 7. A limitswitch (omitted from the drawingsfor clarity) then opens door 36 andreverses pressure to piston 33 to move dolly 31 backwardly toward thepreheating section. As the dolly moves to the right (FIGURE 7) the upperreach 35a of the endless chain will advance to the left. Lug 41 willimmediately engage car 48 and advance it rapidly into heating section45. After -lug 41 and car 48 have advanced a short distance (perhaps 10or 12 inches) lugs 42, 43 and 44wi11 engage cars 49, 50 and 51,respectively, and those cars will also be advanced maintaining a gapbetween cars 48 and 49. When the piston has fully retracted so that itis again in the position shown in FIGURE v6, car 48 will be inside theheating section 45. Door 46 is then automatically lowered by anotherlimit switch. The apparatus then again slowly pushes the train in thekiln in the manner previously described.

Referring now to FIGURES 8, 9 and l0 a dolly 52 is mounted upon the endof a piston rod 53 operable in a hydraulic piston 53a. An endless chainhaving an upper reach 54a and a lower reach 54h passes over sprockets 56and 57. The lupper reach 54a is attached to dolly 52. It will be notedfrom FIGURE 8 that two side-by-side chains are provided. For conveniencelthey a-re given the same reference numbers. A second endless chain(also in duplicate) having an upper reach 58a and a lower reach 58bpasses over sprockets 59 and 60. Lower chain reach -58b is attached todolly 52. Accordingly, upper chain reaches 54a and 58a will move inopposite directions upon movement of dolly 52. In like manner, lowerchain reaches 54b and 58b will move in opposite directions.

The pushing apparatus is positioned outside a kiln in which a heatingsection -66 and a preheating section 67 are provided. Dolly 52 and theassociated .piston and piston rod 53 and 53a are, however, locatedoutside of the heating zone of the kiln and are not exposed to itstemperatures. A door 68 is provided between the heating and preheatingsections and is vertically movable responsive to limit switches. Thoseare conventional and have been omitted from the drawings for simplicity.

A ylug 61 is attached to each upper chain reach 54a, and lugs 62, 63, 64and 65 are attached to each upper reach 58a. A kiln car 70 is shown inthe heating section of the kiln (FIGURES 8 and 9) and a series ofadditional kiln cars 71, 72, 73, and 74 are shown in preheating section67. When dolly 52 is in the position shown in FIGURES 8 and 4 door 68 isclosed. Hydraulic pressure is admitted to piston 53a to begin pushingdolly 52 to the left, as shown in the figures. As dolly 52 moves towardheating section 66, each upper chain reach 54a will move vforwardly withit, moving each lug 61 toward the heating section. After movement ofperhaps a foot, each lug 61 will engage kiln car 70 and will beginmoving lforward the entire train of ears in the heating section of thekiln. Movement of dolly 52 will be rapid until lugs 61 engage kiln car70. Thereafter the movement will be slowed to provide a deliberate push.At the same time that the dolly 52 is moving t-oward heating section 66,upper chain reach 58a and lugs 62, 63, 64 and 65 move away from theheating section 66. When .piston S3 has completed a full stroke dolly 52will be in the position shown in FIGURE 10. .By means of a convention-allimit switch, movement of d-olly 52 is reversed and it is rapidlyretracted causing lug 62 to move away from the heating section and lugs63, 64, l65 and l66 to move toward the heating section. At the timemovement of dolly 52 is reversed, door 68 is opened. Lug 63 willpromptly engage kiln car 71 and advance it into heating section 66.After further movement of dolly 52, lugs 64, 65 and 66 will engage kilncars 71, 72 and 73. Thus, all of cars 71, 72, 73 and 74 will beadvanced, but there will be a gap ybetween cars 71 and 72. When ydolly52 has completed its reverse movement, door 68 is closed by a furtherlimit switch. The kiln cars lat that point are again in the positionshown in FIGURES 8 and 9, but with kiln car 71 at the end of the trainin heating section l66. The cycle is then repeated with a slow pushingstroke and a rapid return stroke, thus enabling almost continuousmovement to be maintained upon the train in the kiln and allowing a newcar t-o be introduced into the kiln without disrupting heating withinthe kiln.

If desired, dolly 52, piston rod 53 and piston 53a may be locatedentirely outside of the kiln heating and preheating sections. All thatis required is to extend the lengths of chains 54 and 58 suiciently tolocate them away from the heated kiln portions.

-Frorn the foregoing it will be seen that a kiln can be pushed on asubstantially continuous basis introducing new cars to the kiln atintervals and maintaining a door at the entrance end to preventinfiltration of cold air at the kiln entrance and disruption of gas owwithin the kiln. At the s-ame time elaborate interlock systemspreviously required are completely avoided and the need for them isobviated.

While I have illustrated and described a present preferred embodiment ofmy invention, itis to be understood that I do not limit myself theretoand that the invention may be otherwise variously practiced within thescope of the following claims.

I claim:

1. Pusher apparatus adapted for use in a continuous tunnel kiln and thelike, said pusher apparatus comprising power means, first lug means indriven relationship to the power means and placed to advance ware in thekiln when the power means are operated, and additional lug means indriven relationship to the power means and driven in opposite directionto the first lug means and placed to advance ware in the kiln, -said lugmeans and said additional lug means being operable `by said power meansalternately to advance ware in the kiln.

2. Pusher apparatus as set forth in claim 1 in which the first lug meansengage kiln car means at a position within the kiln intermediate theentr-ance end and delivery end of the kiln, and the additional lug meansengage kiln car means adjacent to the entrance end of the kiln.

3. Pusher apparatus as set forth in claim 2 in which the addition-al lugmeans are fitted to endless chain means driven by the power means inopposite direction to the first lug means.

4. Pusher apparatus as set forth in claim 3 in which the power meansinclude a uid power piston and having rack and pinion means in drivingconnection between the piston means and the endless chain means.

5. Pusher apparatus as set forth in claim 1 in which the power means isremoved from the heated sections of the kiln.

6. Pusher apparatus adapted for use in a continuous tunnel kiln having apreheating zone and a heating zone,

said pusher apparatus comprising power means, rst lug means in drivenrelationship to the power means and placed to advance ware in theheating Zone when the power means are oper-ated in one direction, secondlug means in driven relationship to the power means and placed toadvance ware from the preheating zone to the heating zone, third lugmeans in driven relationship to the power means and placed to advanceware in the preheating zone, the first lug means being advanced byoperation of the power means in one direction and the second and thirdlug means being advanced by operations of the power means in theopposite direction.

7. Pusher apparatus as set forth in claim 6 in which the first lug meansare connected to a piston and the second and third lug means areconnected to endless chain means and are driven thereby in oppositedirection to the piston by operation of the piston.

8. Pusher apparatus as set forth in claim 6 in which the lug meansengage ware-carrying kiln cars and advance the same through the kiln.

9. The method of charging a continuous tunnel kiln having a preheatingsection and a heating section which comprises slowly advancing ware inthe heating section and thereafter rapidly advancing Ware from thepreheating section to the heating section and simultaneously rapidlyretracting pusher means used to slowly advance the ware in the heatingsection. Y

10. The method of claim 9 which includes opening door means intermediatethe preheating section and heating section after advancing ware in theheating section and during rapid advance of ware from the preheatingsection to the heating section aud then closing the doormeans.

11. The method of claim 10 which includes rapidly advancing ware intothe preheating section substantially concurrently with rapid adv-ance ofware from the preheating section into the heating section.

12. Pusher apparatus as set forth in claim 8 in which the second lugmeans engage a kiln car before the third lug means engages a kiln car.

References Cited UNITED STATES PATENTS 549,962 11/1895 Hemphiu 26a-2sv561,782 8/1923 France.

JOHN I. CAMBY, Acting Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION w Patent NO.3,390,870 July 2 1968 Stephen B. Yacura It is certified that errorappears in the above identified patent and that said Letters Patent arehereby corrected as' shown below:

Column 2, line 33, "heating" should read preheating Column 5 line 70,"4" should read 9 Signed and sealed this 13th day of January 1970.

(SEAL) Attest:

Edward M. Fletch, Jr.. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents

